1. Field of the Invention
The present invention relates generally to improved compositions and methods for sealing pipe in well bores, and more particularly, to such compositions and methods wherein the sealant hardens into a highly resilient solid mass having high bond strength.
2. Description of the Prior Art
Hydraulic cement compositions are commonly utilized as sealants in subterranean well construction and repair procedures. For example, hydraulic cement compositions are used in primary sealing operations whereby strings of pipe such as casing and liners are sealed in well bores. In performing primary cementing, a hydraulic cement composition is pumped into the annular space between the walls of the well bore and the exterior surfaces of pipe disposed therein. The cement composition is permitted to set in the annular space thereby forming an annular sheath of hardened substantially impermeable cement therein. The cement sheath is intended to support and position the pipe in the well bore and bond the exterior surfaces of the pipe to the walls of the well bore whereby the undesirable migration of fluids between zones or formations penetrated by the well bore is prevented.
Set hydraulic cement compositions are brittle solid masses which generally do not have sufficient resiliency to resist the loss of pipe and/or formation bond, cracking or shattering as a result of pipe movements caused by expansion, contraction, impacts or shocks. The bond loss, cracking or shattering of the set cement allows leakage of formation fluids through at least portions of the well bore by way of the annulus therein which can be highly detrimental.
Thus, there are needs for improved pipe sealing compositions and methods of sealing pipe in well bores whereby the hardened compositions are highly resilient solid masses having high bond strengths.